Many microsurgical procedures require precision cutting and/or removal of various body tissues. For example, vitreoretinal surgery often requires the cutting, removal, dissection, delamination, coagulation, or other manipulation of delicate tissues such as the vitreous humor, traction bands, membranes, or the retina. The vitreous humor, or vitreous, is composed of numerous microscopic fibers that are often attached to the retina. Therefore, cutting, removal, or other manipulation of the vitreous must be done with great care to avoid traction on the retina, the separation of the retina from the choroid, a retinal tear, or, in the worst case, cutting and removal of the retina itself.
Microsurgical instruments, such as vitrectomy probes, fiber optic illuminators, infusion cannulas, aspiration probes, scissors, forceps, and lasers are typically utilized during vitreoretinal surgery. These devices are generally inserted through one or more surgical incisions in the sclera near the pars plana, which are called sclerotomies. To establish an entry through the sclera into the posterior segment of the eye, trocar cannulas are typically used. The trocar cannula generally serves as a pathway through which various microsurgical instruments may be delivered to the posterior segment of the eye.
Typically, a surgeon relies upon friction between an outer surface of the trocar cannula and the sclera of the eye to maintain the trocar cannula's position within the eye. However, during an exchange of the microsurgical instruments, there is a risk that the trocar cannula may be inadvertently moved, which may cause injury to the patient. To insure against inadvertent movement of the trocar cannula, in prior art systems a surgeon grasps a cannula hub with a pair of forceps during the instrument exchange to maintain the position of the trocar cannula. Such a practice requires an extra step in the surgical procedure, thereby increasing the length of surgery. In addition, this practice also requires an extra hand to hold the forceps. Therefore, a need remains for an improved retention mechanism for a trocar cannula.